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Infectious Agents > Exam 3: Anaerobic Infections > Flashcards

Exam 3: Anaerobic Infections Flashcards

1
Q

What are the major anaerobic pathogens?

A

GP spore forming rods (clostridium)
GP non-sporeforming rods (actinomyces, propionbacterium, eubacterium)
GN rods (bacteroides and fusobacterium)
GP cocci (peptococcus and peptostreptococcus)

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2
Q

What is the body’s normal flora and mucosal surfaces like?

A

Normal flora: predominately anaerobic

Mucosal surfaces: heavily colonized by obligate anaerobes

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3
Q

Describe the bacteria in the fecal matter of the colon

A

Makes up 90% of fecal matter

Obligate anaerobes outnumber facultative anaerobes by more than 1000:1

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4
Q

Describe the ratio of obligate and facultative anaerobes to other bacteria in the mouth

A

They outnumber other bacteria by more than 10:1

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5
Q

Why can obligate anaerobes survive in the mouth in the presence of oxygen?

A

Because oral/viridans streptococci lower the red-ox potential

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6
Q

What do pathogenic strains of bacteroides and fusobacterium produce as a virulence factor?

A 
Polysaccharide capsules (antiphagocytic)
Bacteroides also produce pili (adherence)
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7
Q

What often contributes to the adherence and cell toxicity of GN anaerobes?

A

Outer membrane proteins, LPS-endotoxin, and other cell surface components

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8
Q

What are common virulence factors?

A

Extracellular or cell-bound enzymes and leukocidins ir cytolysins

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9
Q

What is a virulence factor associated with intracellular activity?

A

Protein exotoxins

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10
Q

What enhances survival and virulence?

A

Synergistic mechanisms

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11
Q

What does Bacteroides spp. require for survival and virulence? Where does it get it?

A

Vitamin K

Gets it from nonpathogenic streptococci or other anaerobes

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12
Q

What does B. asacharolyticus do for survival and virulence?

A

Causes severe spreading of lesions supplied with succinate from klebsiella and other helper bacteria

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13
Q

How do facultative anaerobes provide a more favorable environment? What do anaerobes do with this?

A

By removing oxygen and adding reducing substances as the infection matures
Anaerobes return the favor by producing leukotoxins and depleting opsonins and complement

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14
Q

What clinical feature is consistently associated with obligate anaerobes?

A

A putrid odor

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15
Q

List the remaining clinical features for anaerobic infections

A 
Clostridial myonecrosis
Oropharyngeal and cutaneous infections
Pleuropulmonary infections
Intra-abdominal infections
Osteomyelitis
Reproductive tract infections
*Read these
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16
Q

What are the staining characteristic of bacteroides?

A

GN rods
Very pleomorphic and may be beaded, coccoid, or slender
Often stain poorly and are difficult to see
Sometimes bipolar staining

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17
Q

What are the staining characteristic of clostridium?

A

GP rods
Large, chains
Spores swell the sporangium greatly

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18
Q

What are the staining characteristic of fusobacterium?

A

GN rods

Thin, pale, with tapered or pointed ends and a cigar or needle shape

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19
Q

What are the staining characteristic of actinomyces?

A 
GP rods (or gram variable)
Small, thin
May form branched filaments or tangled mats
May be beaded and poorly visible
May form sulfur granules
20
Q

What are the staining characteristic of peptococcus and peptostreptococcus?

A

GP cocci
Small, singly, pairs, or clusters in pairs and chains
Smaller, but cannot be distinguished from aerobic cocci

21
Q

What are examples of acceptable collection and transport of specimens for culture?

A

Aspirates from enclosed lesions or body sites normally sterile
TTA or lung aspirates
Uterine aspirates
Aspirates of abscesses, deep wound
Tissue obtained from deep infections during debridement
Sequestra, bone biopsies, or nearby soft tissue
Blood
Aspirates from occeous bullae or frontal sinus

22
Q

What are examples of unacceptable collection and transport of specimens for culture?

A 
Swabs of pus from superficial wounds or draining tracts
Urine
Mouth, pharynx, or upper airway swabs
Swabs from vagina. cervix, urethra
Feces
Saliva or nasal exudates
Ear swabs
Cerebrospinal fluid, nasotracheal and bronchoscopic aspirates
23
Q

What are the most efficacious antibiotics for anaerobes?

A

Penicillins
Chloramphenicol
Clindamycin
Metronidazole

24
Q

Which antibiotics are not the most efficacious to treat anaerobes but are often given concurrently to cover GN enterics?

A

Aminoglycosides

25
Q

Which antibiotics are efficacious agains both GN enteric and anaerobes?

A

Some cephalosporins

26
Q

Which antibiotics are not useful for anaerobes?

A

Tetracyclines
Sulfonamides
Trimethoprim-sulfonamides

27
Q

What do C. perfrinigens type A-E all cause?

A

Enteric disease in just about all domestic animals

28
Q

What is bovine liver abscesses most common in?

A

Feedlot cattle fed grain-rich diets that cause rumen acidosis, ruminal epithelial ulceration, and subsequent colonization by Fusobacterium necrophorum, which translocate to liver by the hepatic portal veins

29
Q

What are the bacteria commonly isolated from bovine liver abscesses?

A

A. pyogenes
Enteric
Bacteroides
Staphylococci and steroptococci alone or in combination with F. necrophorum

30
Q

What is footrot in sheep?

A

Economically important contagious disease of the germinal layers of the interdigital skin and horn matrix invaded by B. nodosus and F. necrophorum

31
Q

What is B. nodosus?

A

An obligate parasite of the hoof epidermis of sheep and cattle

32
Q

What happens to wet stratum corneum?

A

It is invaded by F. necrophorum resulting in interdigital dermatitis that the becomes complicated by B. nodosus virulent strains

33
Q

Describe Bacteriodes melanogenicus

A

Suspect any time black pus is present, especially if the pus fluoresces
Fairly common in dogs and cats- pyometras

34
Q

What are characteristics of clostridium?

A

Obligate anaerobes that cannot use oxygen and does rapidly in its presence except for its spores

35
Q

Where can Clostridium perfinigens be found?

A

Most common soil bacterium
Most common anaerobic lab contaminant
In normal intestine of most mammals

36
Q

What is used to test for Clostridium perfinigens?

A

Phospholipase C

37
Q

What are the 5 types of Clostridium perfinigens based on?

A 
The 4major legal toxins produced:
Alpha is produced baby all types
Beta is produced by types B and C
Epsilon is produced by types B and D
Iota is produced by type E
38
Q

What does Clostridium chauvoei cause in cattle?

A

Blackleg

39
Q

What does blackleg result from?

A

The activation of latent spores deposited in muscles after being transported in blood from liver or intestine

40
Q

What does Clostridium septicum cause?

A

Malignant edema
Braxy
Gangrenous dermatitis in chickens

41
Q

What is braxy?

A

When frozen feed damages abomasum

42
Q

What are the 3 types of Clostridium novyi? What toxin do they produce?

A

Type A: alpha, gamma, delta, epsilon
Type B: alpha, beta
Type C: nontoxigeni

43
Q

What does Clostridium novyi cause?

A

Gas gangrene
Bighead in rams
Black disease in cattle and horses

44
Q

What does Clostridium haemolyticum cause?

A

Bacillary hemoglobinuria or redwater disease

45
Q

Read through the handout

A

Read through the handout

Infectious Agents (38 decks)

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